Carburetor



July 21, r1931u w. ScoTjr GARBURETOR Filed Dec. 29. 1925 36 Patented July 21, 1931 UNITED STATES yPATENT OFFICE 'WILLIAM SCOTT, OF MEDFORD, MASSACHUSETTS, ASSIGNOR` TO SELF FEEDING CARBU- AZREITOIEK, COMPANY, INC., OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSA- CHUSETTS CARBURETOR Application filed December 29, 1925. Serial No. 78,075.

This invention relates to carburetors and especially, although not exclusively, to carburetors adapted for use in internal combustion engines, an object of the invention being to provide animproved self-'contained carburetor having vacuum or pressure operating means for causing the feed of fuel directly thereto from a supply at a lower level without the interposition of the usual vacuum tank or the like.

In accordance with the preferred form of my invention, the spray nozzle or fuel jet of the carburetor is supplied with fuel from a supply chamber constructed to form a combined vacuum tank'and float chamber, the

fuel being supplied to the chamber directly from a source of lsupply by suction, as from the intake of the engine. The relation of the fuel level in the float chamber to the fuel nozzle is such that the fuel will be fed from the float chamber to the spray nozzle by gravity under the control of valve mechanism which is operated by suction when the englne 1s runmng.

A further object of this invention is to provide an improved carburetor wherein fuel is supplied to the spray nozzle, by gravity and under the control of engine suction, directly from a fuel or float chamber, and wherein the fuel chamber is supplied with fuel b vacuum or suction directly from the main uel tank. As a result of this invention a simplified fuel feed and .carbureting system is provided,

which is more positive and efficient in operation, and wherein the necessity of employing a separate vacuum tank and grav-ity feed therefrom to the float chamber of the carburetor is eliminated.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming apart of this specification, wherein like .reference characters designate corresponding parts inthe several views, and wherein:

Fig. l is a cent-ral vertical section of a cary bureting device embodying" my invention.

Fig. 2 is a fr stantially on line 2 2, Fig. 1, looking inthe direction of the arrows.

agmentary section taken sub-l Fig. 3 is a fragmentarysecton taken subthe direction of the arrows.

Fig. 4 is a sectional view, reduced in size, similar to Fig. 1 but illustrating the mechamsm when the engine is notrunning.

Before explaining in detail the present improvement and mode of operation thereof,

Vstantially on lines 3--3of Fig. 2, looking in I desire to have it understood-that the invention is not limited to the details of construcltion and arrangement of parts which are illustrated in the accompanying drawings,

a suitable casing 20 within which is located the usual mechanism for supplying a proper fuel mixture to the engine. It will be understood that the present invention is not limited to the instrumentalities shown for providing the fuel mixture, since any desired type of carburetin instrumentalities may be utilized in connectlon with my invention. In the present instance the top of the casing 20 is provided with a supporting flange 20a upon which is mounted a fuel or iicat chamber casing 21.4 This casing is rovided internally thereof with bosses 22 an the float chamber is secured to the casing 20 of the carburetor by means of bolts 23 extending through the Bange 20a and into the bosses or lugs 22. The adjacent top and bottom walls respectively'of-the'casing20 and the iioat chamber- 21'are bored and counterbored to receive a valve casing 24 which is held therein as illustrated in Fig. 1, this casing extending transversely and vertical;7 through the casing 20 and at its lower en fitting securely into aboss 25 extending from the bottom wall of.J

tapered portion 28a adapted to be seated against the lower end of the valve casing 24. The valve 28 is formed on the end of a lifting pin 286 which fits loosely in a central recess 30 in the casing 24, and the pin 285 is provided with an extension 280 of reduced tendingfreely through the guide tube 32 is a valve comprising a stem 34 terminating at the lower end thereof in a tapered valve portion 35 adapted at predetermined times to be seated against the upper end of the passage or duct 31 as illustrated in Fig. 4.

IThe fuel or float chamber 21 is supplied with fuel from a suitable source of supply through a pipe 36 'threaded into the upper end of the cap 33. As illustrated in Fig. 4 the pipe 36 conducts fuel from a fuel tank T, this tank being shown below the level of the carburetor. As illustrated especially in Fig. 1, the cap or cover 33 of the fuel chamber is provided with a chamber 38 communicating by means of a port 37 with the feed pipe 36, and within the chamber or recess 38 projects atapered valve 39 adapted in the position shown in Fig. 1 to be seated in the port 37, thereby closing the same. The valve 39 is provided with a projecting flange 40 and depending therefrom is aV projecting stem 41 adapted to be guided within the upper end of the guide tube 32. A suitable float 42 is guided on the tube 32, and as shown in Fig. 1, and is soldered or otherwise secured to the flange 40 of the valve 39, so that when the fuel in the chamber 21 is at its highest level, the fioatF 42 will move the valve 39 into position to close the port 37. As the level of fuel in the chamber 21 drops the valve 39 will move by gravity into posit-ion to open the port 37, and this movement is limited by engagement of the flange 40 with the upper end of the guide tube 32.

Within the carburetor casing 20 the valve casing 24 is provided with a boss 45 tapped to receive the threaded end of a spray nozzle 46 and extending through the spray nozzle is a meterin pin 47 which is adjusted as hereinafter escribed for the purpose of varying the mixture. The fuel within the fuel or float chamber 21 is conducted or supplied t/o the spray nozzle 46 by means of a conduit which in the presentinstance comprises openings or ports 44 in the upper end of the casing 24 which connect the chamber 21 with the vertical passage 31. lit will be noted that the lifting pin 282) and its eXtension 280 are of smaller diameter than the passagesor conduits 30 and 31, so that the fuel may flow from the chamber 21 through the ports 44 and downwardly by gravity around the lifting pin to the spray nozzle 46. A screen or filter 440 may be placed over the upper end of the casing 24 so that the fuel will How through this screen into the ports or passages 44. f

The metering pin 47 extends throughthe spray nozzle 46 and through a slot 48 in the valve lifting pin 282) (see Fig. 2) and the other end of the metering pin exteriorly of the casing 24 is provided with annular rack teeth 49 meshingwith ajpinion 50 secured to the inner end of a rock shaft 51. This shaft is carried in a detachable bearing 52 secured to the carburetor casing, and at its outer end is mounted a swinging adjusting arm 55. As shown in Fig. 2, this arm is bent inwardly and is tapped to receive an adjusting screw 56 adapted to abut against a lug 200 (see also Fig. 3)'on the carburetor casing. Connected to the arm at the opposite side of the shaft 51 is an operating arm 57, which may be connected by a rod or wire 58 to permit the operation thereof at the dash by the driver of the vehicle. As shown in Fig. 2, an annular flange 53 is formed on the shaft 51 and abuts against a shoulder formed in a counterbore of the casing, and interposed between this collar and the bearing 52 is a spiral spring 54 which acts to maintain the gear 50 and rack 49 in operative relation.

From this construction it will be seen that the rod 58 (see Fig. may be operated in either direction by the operator of the vehicle to swing arm 57, thereby rocking the shaft 51, and through the medium of the pinion 50 and rack teeth 49 the metering pin 47 may be shifted endwise. By adjusting the screw 56 the position of metering pin 47 will be determined so as to rovide the proper mixture when the engine 1s idling.

As hereinbefore stated the carbureting instrumentalities by means of which the mirrture is obtained may be of any standard type, and in the present instance by way of example the carburetor is shown as provided with a Venturi opening 58 adjacentrto the intake manifold or suction side of the engine, a hot air intake 66, and a throttle valve 67 for controlling the 'flow of air. fn the present construction the wall of the carburetor casing is drilled to provide a duct 60 con nected by means of a duct 59 with the outlet of the carburetor between the spray nozzle and the intake of the engine. rlhe duct or passage 60 communicates with a pipe or tube 61 secured within the float chamber 21, this pipe extending vertically through the float chamber and having the upper end open as shown at 62 above the level of ,fuel in the chamber. rllhe wall of the carburetor casing is also provided with a duct or passage 64, in

the present instance located in the opposite wall below the. passage 60, and the duct 64 communicates with the Venturi opening by means of a duct 63 and leads to the upper side of the piston 127.

rl'he chamber 21 `is air tight and entirely sealed from the outside atmosphere, a sealing gasket 16 being interposed between chamber 21 and casing 20, and a similar gasket 17 between the cap orcover 33 and the chamber 21. A removable plug 11 may be provided to permit the emergencyfilling of the chamber 21. The piston 27 is preferably formed with recesses 13,and 14 at opposite faces thereof to prevent the sealing or freezing of the piston within the cylinder due to the prese ence of water therein, as by condensation, or by separation from the gasoline, or otherwise. These recesses communicate with each other through the medium of a bleeding port 12 and a transverse groove 15 at the lower end of the valve 28, the latter groove also serving as a means for receiving a valve grinding tool. Y

From the foregoing the operation of the present invention may be readily understood. When the engine is not running the mechanism will occupy the positions shown in Fig.

t. Upon Startinsr up the engine the suction at the outlet 58 of? the carburetor will be communicated through the passages 63 and 611 to upper end of the piston 27, thus raising the piston within the cylinder 26. This will result in raising the valve 28 and seat. ing the saine against the lower end of the valve casing 24:, thereby closing the lower end of the latter. Ait the same time the lifting pin 236 of the valve 28 will be shifted upwardly intoiengagementvvith the valve 35, thereby raising this valve from its seat and opening the passage 31 to lthe ioat chamber 21. iit the same time the engine suction at the outlet 53 of the carburetor will be transmitted through passages 59 andl 60 and pipe 61 to the upper end ofthe oat chamber 21, 21, thereby tending to set up a partial vacuum in the space above the level of the fuel. As

long as the float l2 is in the position shown in Figi with the valve 39 closing the passage 37, no fuel will be drawn into the fuel 'p or heat chamber 21o Delivery of fuel from the chamber 21 to the spray nozzle 46 will tend te reduce the level of fuel withinsald chamber, resulting in immediately lowering the valve 39 and permitting a supply of fuel to be fed from the tank '.l through ipe 36 into the fuel chamber on account of t e partial vacuum established within the latter. rl'herefore it will be seen that with the engine operating under normal or average conditions the fuel level within the oat chamber will tend to remain constant and hence the valve 39 will remain in a dehnite position with relation to the port 37 which communicates' with the feed line, permitting a flow of fuel Iinto the fica-t chamber substantially equal to lnot elevate the fuel from the supply tank to the fuel chamber at a rate sufficient to compensate for the flow of fuel to the spray nozzle. The subatmosphereic pressure at the spray nozzle is balanced by the equal pressure in the fuel chamber 21, and hence the feed of fuel from the fuel chamber to the spray nozzle will be by` gravity under the Weight of the fuel itself.

It Will therefore be noted that I have provided an improved carbureting mechanism in which a fuel chamber is associated with the carburetor proper to constitute a selfcontained unit. Also by virtue of this in vention, I amable to provide a carbureting system wherein a single fuel supply chamber is adapted to perform the functions of both the usual float chamber and the usual vacuum tank,'and wherein a vacuum feed is provided directly from the main fuel tank of the vehicle to the fuel chamber of the.car, buretor thus doing away with a separate vacuum tank mechanism commonly used in automotivev vehicles. It will be seen that the flow of fuel from the fuel chamber to the Spray nozzle is by gravity, the rate thereof being governed by the suction of the engine, and at the same time the suction of the engine will vary the pressure above the fuel level in the float chamber, tending to form a vacuum therein, thus governing the feed from the supply tank directly to the 'fuel' chamber. Since in the present instance the flow of fuel from the chamber 21 to the spray nozzle is by gravity, the valve 35 is provided to cut off this flow. The piston 27 maintains the valve 35 open at all times while the engine is running, the piston being raised at all engine suctions, and descending to the position shown in Fig. i to permit valve 35 to cut off the passage 31 only when the engine stops. 7 l v What I claim is:

1. 1n a carbureting system, in combina tion, a fuelnozzle vhaving a needle valve, a fuel chamber having a passage to said nozzle and Aarranged Ato fuel thereto by gravity, a valve for opening and closing said passage, means operated by engine suction for controlling said valve, va .feed conduit connecting said chamber with a source of supply, a valve for opening and closing said conduit, a ioat within said chamber for operating said valve, and 4rneans for varying by suction the pressure within said chambery to provide a vacuum thereto from the source of supply.

2.' n a carburetor, the combination of a fuel nozzle having a needle'valve, a float chamber, a. fuel passage from said chamber to the nozzle, means for providing a vacuum feed from a source of supply to said chamber, a valve for controlling the flow of fuel through said fuel passage, a piston chamber, a piston therein for operating said valve, and a conduit communicating with said piston chamber independently of said fuel passage for operating said piston by engine suction.

-V3. In a carburetor, a fuel nozzle having a needle valve, a fuel chamber arranged to feed fuel to said nozzle by gravity, a fuel passage connecting said chamber and nozzle, a valve for controlling the flow of fuel through said passage, and means including a conduit separate from said fuel passage and leading to the outletof the carburetor for operating said valve by engine suction.

4. In a carburetor, a fuel nozzle having a needle valve, a chamber arranged to feed fuel by gravity to said nozzle, a fuel passage between said chamber and nozzle, a valve for controlling the flow of fuel through the passage, means separate from said fuel passage for subjecting the fuel chamber to en ine suction, and means separate from said uel passage for operating said valve by engine suction.

5. In a carburetor, a fuel nozzle having a. needle valve, a float chamber, a fuel passage from said chamber to the nozzle, a valve extending within said float chamber for controlling the flow of fuel through said passage, and means for operating said valve by engine suction independently of the flow of fuel from the chamber 'to the nozzle.

6. In a carburetor, a fuel nozzle having a needle valve, a fuel chamber, a fuel passage including a valve seat, a valve normally seated on said seat to close the fuel passage, and a piston actuated by engine suction independently of the flow of fuel for raising said valve.

7. In a carburetor, a casing, a horizontal fuel nozzle therein provided with an adjustable needle valve to control the discharge of fuel through the nozzle, a float chamber mounted on said casing, a fuel passage for conducting fuel by gravity to said nozzle, a valve for opening and closing said passage,

' means for opening said valve during operasaid suction is applied and for closing such communication when said suction is discontinued.

9. In a carburetor, in combination, a fuel nozzle having a needle valve to control the mixture. a float chamber connected with a source of fuel supply, subjected to engine suction, and arranged to. feed fuel to said nozzle by gravity, a self-closing valve for controlling communication between said chamber and nozzle, and means operated by engine suction for opening said last-named valve.

l0. In a carburetor, in combination, a fuel nozzle having a needle valve to control the mixture. a float chamber connected with a source of fuel supply, subjected to engine suction, and arranged to feed fuel to said nozzle by gravity, a valve for controlling communication between said chamber and nozzle, and

means for automatically opening said valve during operation of the engine and for permitting ,it to close when the engine stops.

l1. In a carburetor, in combination, a fuel nozzle having means to control the mixture, a fuel chamber arranged to feed fuel .directly to said nozzle by gravity, and means independent of said mixture controlling means for automatically establishing communication between said chamber and nozzle during 4operation of the engine and for automatically closing the same when the engine stops.

12. In a carburetor, in combination, a fuel nozzle having means to control the mixture, a fuel chamber arranged to feed fuel directly to said nozzle by gravity, and means independent of said mixture controlling means and controlled by engine suction for automatically establishing communication between said chamber and nozzle during operation of the engine and for automatically closing the same when the engine stops.

13. In a carburetor, in combination, a fuel nozzle having a, needle valve or metering pin to control the mixture, a. fuel chamber arranged to feed fuel directly to said nozzle by gravity, a. valve independent of said needle valve or metering pin for controlling communication between said chamber and nozzle, and means for automatically opening said last-named valve during operation of the engine and for permitting it to close when the engine stops.

14. In a carburetor, in combination, a fuel nozzle having a needle valve or metering pin to control the mixture, a fuel chamber arranged to feed fuel directly to said nozzle by gravity, a valve independent of said needle valve or metering pinfor controlling communication between said chamber and nozzle, and means controlled by engine suction for automatically opening said last-named valve during operation of the engine and for permitting it to close when the engine stops.

In testimony whereof I affix my signature.

WILLIAM SCOTT. 

